This invention relates to improvements in a miniaturized electronic apparatus using a solar battery as a power source and having a liquid crystal display unit.
A miniaturized electronic apparatus, e.g., an electronic calculator or timepiece, which uses a solar battery and has a liquid crystal display unit, is well known in the art. Such a miniaturized electronic apparatus requires a large number of external components, in addition to the solar battery and liquid crystal display unit, such as a printed circuit board connecting the battery and display unit, and LSI. The external components further include diodes for source voltage regulation, capacitors for stepping up voltage to the liquid crystal, resistors for a pulse generator and capacitors for power source protection. The use of these external components increases the price of the miniaturized electronic apparatus. Further, since a large number of components are involved, it is difficult for an automatic assembling apparatus to assembly the electronic apparatus.
The liquid crystal display unit is usually driven by either a static drive system or a time-sharing drive system. When the static drive system is used, the liquid crystal display unit must have a large number of connection terminals and consumes much power. The miniaturized electronic apparatus using a solar battery as power source can not be driven by the static drive system, because of low power-generation capacity of the solar battery. When the time-sharing drive system is used, flicker of the display is liable to result. In addition, when this system is used, three or four different voltages must be applied to segment electrodes. This requires circuit exclusively for generating these voltages. Hence, the time-sharing drive system needs to have a complicated driver circuit.